Kyle is an environmental scientist studying land-based solutions to climate change. With expertise at the interface of ecosystem ecology and climate science, he uses observational, modeling, and synthesis techniques to understand how natural and working lands can be harnessed to aid in climate change mitigation and adaptation. Kyle has worked across a variety of landscapes from the upland sub-tropical forests of southeast Asia to the subsided peatlands of the California Delta to better characterize the potential for ecosystems to be part of the solution.
Bachelor of Arts, Colorado College, Environmental Science, chemistry concentration (2011)
Doctor of Philosophy, University of California, Berkeley, Ecosystem Sciences, Biometeorology (2019)
Chris Field, Postdoctoral Faculty Sponsor
- Wildfire-Smoke Aerosols Lead to Increased Light Use Efficiency Among Agricultural and Restored Wetland Land Uses in California's Central Valley JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 2020; 125 (2)
- Assessing the carbon and climate benefit of restoring degraded agricultural peat soils to managed wetlands AGRICULTURAL AND FOREST METEOROLOGY 2019; 268: 202–14
- A Biogeochemical Compromise: The High Methane Cost of Sequestering Carbon in Restored Wetlands GEOPHYSICAL RESEARCH LETTERS 2018; 45 (12): 6081–91
Methane Emissions Reduce the Radiative Cooling Effect of a Subtropical Estuarine Mangrove Wetland by Half.
Global change biology
The role of coastal mangrove wetlands in sequestering atmospheric carbon dioxide (CO2 ) and mitigating climate change has received increasing attention in recent years. While recent studies have shown that methane (CH4 ) emissions can potentially offset the carbon burial rates in low-salinity coastal wetlands, there is hitherto a paucity of direct and year-round measurements of ecosystem-scale CH4 flux (FCH4 ) from mangrove ecosystems. In this study, we examined the temporal variations and biophysical drivers of ecosystem-scale FCH4 in a subtropical estuarine mangrove wetland based on three years of eddy covariance measurements. Our results showed that daily mangrove FCH4 reached a peak of over 0.1 g CH4 -C m-2 day-1 during the summertime owing to a combination of high temperature and low salinity, while the wintertime FCH4 was negligible. In this mangrove, the mean annual CH4 emission was 11.7 ± 0.4 g CH4 -C m-2 year-1 while the annual net ecosystem CO2 exchange ranged between -891 and -690 g CO2 -C m-2 year-1 , indicating a net cooling effect on climate over decadal to centurial timescales. Meanwhile, we showed that mangrove FCH4 could offset the negative radiative forcing caused by CO2 uptake by 52% and 24% over a time horizon of 20 and 100 years, respectively, based on the corresponding sustained-flux global warming potentials. Moreover, we found that 87% and 69% of the total variance of daily FCH4 could be explained by the random forest machine learning algorithm and traditional linear regression model, respectively, with soil temperature and salinity being the most dominant controls. This study was the first of its kind to characterize ecosystem-scale FCH4 in a mangrove wetland with long-term eddy covariance measurements. Our findings implied that future environmental changes such as climate warming and increasing river discharge might increase CH4 emissions and hence reduce the net radiative cooling effect of estuarine mangrove forests.
View details for DOI 10.1111/gcb.15247
View details for PubMedID 32574398
Soil properties and sediment accretion modulate methane fluxes from restored wetlands
GLOBAL CHANGE BIOLOGY
2018; 24 (9): 4107–21
Wetlands are the largest source of methane (CH4 ) globally, yet our understanding of how process-level controls scale to ecosystem fluxes remains limited. It is particularly uncertain how variable soil properties influence ecosystem CH4 emissions on annual time scales. We measured ecosystem carbon dioxide (CO2 ) and CH4 fluxes by eddy covariance from two wetlands recently restored on peat and alluvium soils within the Sacramento-San Joaquin Delta of California. Annual CH4 fluxes from the alluvium wetland were significantly lower than the peat site for multiple years following restoration, but these differences were not explained by variation in dominant climate drivers or productivity across wetlands. Soil iron (Fe) concentrations were significantly higher in alluvium soils, and alluvium CH4 fluxes were decoupled from plant processes compared with the peat site, as expected when Fe reduction inhibits CH4 production in the rhizosphere. Soil carbon content and CO2 uptake rates did not vary across wetlands and, thus, could also be ruled out as drivers of initial CH4 flux differences. Differences in wetland CH4 fluxes across soil types were transient; alluvium wetland fluxes were similar to peat wetland fluxes 3 years after restoration. Changing alluvium CH4 emissions with time could not be explained by an empirical model based on dominant CH4 flux biophysical drivers, suggesting that other factors, not measured by our eddy covariance towers, were responsible for these changes. Recently accreted alluvium soils were less acidic and contained more reduced Fe compared with the pre-restoration parent soils, suggesting that CH4 emissions increased as conditions became more favorable to methanogenesis within wetland sediments. This study suggests that alluvium soil properties, likely Fe content, are capable of inhibiting ecosystem-scale wetland CH4 flux, but these effects appear to be transient without continued input of alluvium to wetland sediments.
View details for DOI 10.1111/gcb.14124
View details for Web of Science ID 000441746900019
View details for PubMedID 29575340
- A Unique Combination of Aerodynamic and Surface Properties Contribute to Surface Cooling in Restored Wetlands of the Sacramento-San Joaquin Delta, California JOURNAL OF GEOPHYSICAL RESEARCH-BIOGEOSCIENCES 2018; 123 (7): 2072–90
- The effect of land cover type and structure on evapotranspiration from agricultural and wetland sites in the Sacramento-San Joaquin River Delta, California AGRICULTURAL AND FOREST METEOROLOGY 2018; 256: 179–95
- Field-Scale Assessment of Land and Water Use Change over the California Delta Using Remote Sensing REMOTE SENSING 2018; 10 (6)
- Evaluation of Density Corrections to Methane Fluxes Measured by Open-Path Eddy Covariance over Contrasting Landscapes BOUNDARY-LAYER METEOROLOGY 2017; 165 (2): 197–210